Automatic leveling mechanism for concrete slab laying machines



July 29, 1958 w. EARLEY ETAL 2,844,882 AUTOMATIC LEVELING MECHANISM FORCONCRETE SLAB LAYING MACHINES Filed Oct. 17, 1955* 4 Sheets-Sheet 1INVENTORS wilburEarZey BY Rebel-Z LPucIceH July 29, 1958 w. EARLEY ET ALI 2,

AUTOMATIC LEVELING MECHANISM FOR CONCRETE SLAB LAYING MACHINES 4Sheets-Sheet 2 Filed Oct. 1'7, 1955 l a N a v a N INVENTORSwzZburEaJ'Zey BY P0be1'iL Puckeit MI. W

July 29, 1958 AUTOMATIC 'LEVE EKRLEY ETAL 2,844,882 LING HANISM FORCONCRETE SLAB LAY MACHINES Y 4 Sheets-Shet 3 MEC ING Filed Oct. 1'7,1955 v\ hm m m R. m (4 w B July 29, 1958 w. EARLEY ETA]. 2,

I AUTOMATIC LEVELING MECHANISM FOR CONCRETE SLAB LAYING MACHINES FiledOct. 17, 1955 4 Sheets-Sheet 4 INVENTORS wiZburEarZey Robez-Z L.PackeZZRTTYS United States Patent AUTOMATIC LEVELING MECHANISM FOR.CON-- CRETESLAB LAYENG MACHINES Wilbur Earley and Robert L. Puckett, Stockton,Califa,

assignors; to Guntert & Zimmerman Const. Div., Inc., a corporationofCalifornia Application October 17, 1955, Serial No. 540,808

16-Claims. (Cl. 33-185) This-inventiomrelates. to concrete-slab: layingmachines, such as thoseusedto lay landing-strips at airports, lininglarge irrigation ditches, and other concrete-laying. projects of?considerable magnitude.

Such machines straddle-the. area tobe covered or lined;andaresupportedon rails laid to the sidesof said-1 area; sot-that themachine can be advanced to-make. a continua ous; pour.

Incrder to meet specifications asto minimum concrete thickness,.and toavoid the loss to the contractor which would; be. caused by anunnecessarily thick pour, it is: essentiaLthat the machine, shall becontrolled, as to its level; so that" the concrete aspoured shall bemaintained. at a predetermined thickness, within close limits.

Such control can be maintained roughly by a proper setting of the.supporting rails, but it-has, beenfound to bet-impractical to set therails to the accurate level-necessary to. provide the desired closecontrol of thickness'of the: concrete, which must be maintained withinrelatively small fractions of. an inch.

It is therefore the major object of our invention to providea controlmeans. for a slab-laying machine which will automatically maintain themachine, as it advances,

.ata predetermined and accurately held: level, regardless of. anyvariations in:the level of the supporting railsof the machine.

Another: object of the-invention is to arrange the con trol: means: so:that it may beactuated automatically or manually,.as=may be desirable ornecessary attimes.

Still, another object of: the'invention is to provide a practical andreliable automatic leveling mechanism for; concrete slab layingmachines, and one'which will be exceedingly effective for. the purposefor which his; designed.

Theseobjectsxare' accomplished-by. means of such. structureand; relativearrangement of parts as willfully appear by; a perusal of thefollowingspecification and claims-.-

In the drawings:

l-Tig. 1* is a: diagrammatic and-foreshortened end outline of. a slablaying machine, equipped: with our. improved. level control mechanism.

Fig. 2 isanenlarged side elevatiompartly in section,ofone;ofthezleveling control arm units, detached.

Fig; 3. is1a top planview of an arm unit, partly'in section; on. line3-3: of Fig. 2, and shown. in COIlIlfiCe: tion withagrade wire: and; oneof: the'supporting posts therefoiz.

Fig: 4 issantenlarged (full size) sectional'elevationof: the.:fee1er-.and. switch-tilosihgportbn of an armaunit; the:view.being.on.line-44'of'Fig. 3.

Fig. 51- is adiagramof thefluid control: and: electricalsystem;forreachram of the. leveling mechanism;- I

Fig. 6;-is:a;,side elevation of one of; the fluid. control; valvesshowing; the electrical and manual control means therefor;

Referring. now more: particularly'to. the drawingssand;

to. the characters of reference marked thereon, the slab laying machine.itself may be of any existing form, such as that contemplated by PatentNo. 2,549,953, dated April 15, 1951, to L. R. Zimmerman. Such a machineincludes an upstanding frame structure 1 of. a suitable width to:straddle the concrete slab 2" to be poured by the machine,. and whichslab is confined byv side skirts 3' on the frame, and its thicknessdetermined by a smoothing blade 4 rigid with the frame.

The. frame. structure 1 is rectangular or. four-cornered in plan, and ateach corner said. structure is supported by a unit 5 whichincludes awheeled truck 6 riding on.a

rail 7 laid lengthwise of the intended direction of travel ofthe.machine, which is lengthwise of? the slab. ofcon'r cretetobe laid; Asingle rail on each side of the machine supportsiboth trucks 6 on thecorresponding sideof: said machine.

Each. unit 5 includes an upstanding hydraulic jack 8; the-cylinder fwhich is rigidly connected to the frame structure 1 .by a bracket 1%;while. the piston rod 11 of thejack isrconnected to truck 6.

Admission of fluid under pressure to the top of: any jack causes theframe structure 1. to be raisedv at the corresponding corner, whilerelease of the fluid allows said structure to drop.

The units'5 are preferably of. the type shown in said Pate entNo.2,549,953,'or as shown in Patent No. 2,549,954.

Therfeeding'of thefiuid to,- orrelease'ofthesame-from; thejacks isautomatically and independently controlled; was to. maintain the machineat a predetermined. level as it: advances, by the following mechanismsDepending from each jack 8 laterally out from. and clear of the.corresponding truck 6' is a bracket. 12 on which is secured a Ushapediyoke13, vertically disposed and: opening: laterally out. Turnablymounted in bear ings. 141 at the outer end of the yoke is a' screw shaft15; which is held against axial movement in said bearings; A crankhandle 16 is;mounted onthe upper end of; the shaftso; that it may,be'readily rotated byhand;

Threaded-011' the screw shaft 15 is, a hub 17 from which horizontallyspacedarms 18 project laterally out, or so. as. to. extend transverselyof the direction of. movement ofrthexmachine. The. arms are yieldablymaintained in such transverse position by suitable means, such as avertical-axis roller 19 mounted on a support 29 slidable in. a housing21 projecting'from. the'hub li' opposite the armsi18.

A. spring. 22' in thehousing 21? presses the supportaZt);radialIy'of'the. hub. so that the roller 19 frictionallyen: gages avertically elongated horizontally curved track plate. 23. secured on thebackof the-yoke 13.

Theplate; is formed with a 58211;.24 for the roller which releasablyholds said roller so that the arms 18 arexthen in saidtransverse'position. The plate 23 is curvedi on both sides-'of the. seatso as to be eccentricitoxthe. shaft; andisarrangedi so that the spring22 is increasingly com: pressed. as'the; arms 18 swing to one: side orthe; other; andithus tends toreturn said roller toits'normal seatedposition... The. purpose of this feature will be seen later.

Disposed between the arms 18 at their outer end is a-hub' member 25turnably supported from the arms by trunnions-2'6 set horizontally andnormally lengthwise of tlievmachine. The/back side of-the member. 25.isformed with, a zdepression lixin which a spring-pressediroller 28:seats; saidtroller being'supported from the hub 17 and disposedbetweenthe arms 18.

Atubular. rigid: rod-like. arm 29 projects: laterally out from. themember. 25; and at its outer end: is rigidly. connected 10. 811elongated block 30 of dielectric: ma-- terial, and formed with ahorizontal elongated slot' 31 opemtorthe: outer endiofisaid block;Each'iarm 18;. to-

gether with arm 29 and block 3%), actually form a single arm unitconsisting of inner and outer portions. Upper and lower resilientcontact or feeler strips 32 and 33 extend lengthwise of the block withinthe slot 31 and clear of the upper and lower edges thereof, so as to beexposed in said slot. Strips 32 and 33 are normally clear of butengageable with vertical terminal posts 34 and 35, respectively andwhich are mounted in block 30. The strips at their inner end areconnected to a common mounting block 36 secured in the block 30.

For each jack 8 the following control arrangement is provided as shownin Fig.

A wire 37 extends from post 34 through arm 29 and a passage 38 in hub 25to a relay 39 on the machine. Another wire 40 leads from post 35 to arelay 41, while a third wire 42 leads from block 36 to a source ofelectrical energy (such as a battery 43) on the machine. Another wire 44leads from source 43 to relay 39, while yet another wire 45 leads fromsaid wire 44 to relay 41. The relays 39 and 41 include normally openswitches 39a and 41a, respectively, and which are interposed in thewires 44 and 45, respectively. A solenoid 46 is arranged for actuationupon energization of relay 39, while an opposed solenoid 47 is arrangedfor actuation upon energization of relay 41.

The solenoids are mounted in connection with a supporting base 48 on themachine in axially alined but spaced relation, and are provided with amovable core unit C common to both solenoids (see Fig. 6).

Mounted on the base 48 in vertically spaced relation to the solenoids isa valve 49. This valve is of conventional piston type, with the axis ofthe piston 49a parallel to the axis of the solenoids. A pressure pipe 50leads to the valve 48 from a hydraulic pump 51 which takes from a supplytank 52.

Another pipe 53 leads from the valve to the corresponding jack 8, whilea third pipe 54 leads from the valve to tank 52. The valve is of thattype which with one position of the piston thereof will place pipes 50and 53 in communication with each other to feed fluid to the jack; in asecond position of the piston the pipe 53 will be blocked off so as tohold the fluid within the jack; while in a third position of the piston,the pipe 53 will be placed in communication with the return pipe 54 soas to relieve the fluid from the jack. The second or central position ofthe valve piston is in the normal position, when both solenoids aredeenergized, and is that shown in Figs. 5 and 6.

To shift the piston of the valve in one direction or the other from saidcentral position upon energ lation of one solenoid or the other, a lever55 is pivoted intermediate its ends on base 48 at a point between theaxis of the solenoids and that of the valve piston 56. The lever ispivoted, with loose-play in a vertical direction, to the core unit C andto the piston 56, as shown at 57 and 58, respectively.

In order to enable the valve to be manually actuated when desired, thelever 55 above the valve is extended to form a handle 59; thepossibility of a concurrent electrical actuation of the valve takingplace being prevented by the provision of a hand switch 60 in the powerlead 42; which switch, when opened, preventing energizing of thesolenoids. p

The valve, solenoids, and electric circuits leading thereto are arrangedso that when feeler strip 32 contacts post 34 a circuit will be closedand solenoid 46 will be energized to cause the valve piston to beshifted in a direction to feed fluid to the jack 8 so as to raise theframe structure 1. When the strip 33 contacts the post 35 a circuit willbe closed to energize solenoid 47,

causing the valve piston to be shifted so that fluid will' be releasedfrom the jack 8, and the frame structure 1 will be lowered.

Such alternate engagement of one contact strip or the other with thecorresponding terminal posts is effected with any slight verticaldeviation of the machine from a predetermined level, as said machinemoves along the rails 7, by means of grade wires 61, one on each side ofthe machine, or for. each pair of jacks on said side, and extendinglengthwise of the direction of travel of the machine, in mutuallyparallel alinement in a horizontal plane. Each wire is supported atintervals by brackets 62, each projecting radially. from a sleeve 63slidably adjustable on a post 64 adapted to be driven into the ground.

The posts are set so that the blocks 30 will clear the same as they movealong; the wire being taut and being then in the slot 31 intermediatethe ends thereof, and between the strips 32 and 33 initially clear ofboth such strips, as shown in Fig. 4. It will of course be understoodthat the one wire, on each side of the machine, passes through the slotsof the two blocks on the same side of the machine, while separately andindependently effecting the actuation of the corresponding circuits andsolenoids.

The wires 61 must of course be set at a level within the range ofvertical adjustment of the blocks, and to dispose the wire in the propercentralized relation to the strips 32 and 33, it is only necessary torotate the screw shaft 15 in one direction or the other, which raises orlowers the hub 17 and parts attached thereto, and which include theblock 30. Once the proper level of the block 30 has been effected,further rotation of shaft 15 relative to hub 17 is prevented by locknuts 65 on shaft 15, and which clamp the hub to the shaft.

It will therefore be seen that as the machine moves along, anyappreciable drop or lift of the frame structure 1 at any corner will betransferred to the corresponding block 30 to a greater extent.Therefore, with the wires 61 properly taut, such drop or lift will causethe wire to engage one or the other of the contact strips, and force thesame into engagement with the corresponding terminal post, closing thecircuit and energizing one or the other of the solenoids with the resultpreviously described.

While the posts 64 are set clear of each block 30, the brackets 62 arein the path of movement of said block. The block when coming in contactwith the brackets upon advance of the machine therefore swings back,turning about and with the shaft 15 as an axis until the block clearsthe bracket. The block then returns of itself to its normal laterallyprojecting position due to the action of the eccentric track plate 23 onthe spring-pressed roller 19.

Each jack 8 is controlled in its operation by its own valve and solenoidmechanism, but it will be understood that all of the valves for the fourjacks are arranged as a single unit or bank, and one pump supplies fluidto all the valves. Similarly, a single source of electricity suppliesenergy for all the solenoids of the valves, without affecting theirindividual operation.

It will be noted that signal lights 66, one for each solenoid, aremounted wired in parallel in connection with the circuits of saidsolenoids, so that an operator, watching the operations of the machine,may know whetherand how the control mechanism is functioning.

In order, however, that the valves 49 may be manually actuated ifdesired or necessary due to solenoid failure, while still utilizing thesignal lights as an indicating means, a hand switch 67 is interposed inwire 44 beyond the connection of wire 42 with the battery 43. Openingthis switch will therefore, immobilize the solenoids,

enabling the valves to be hand-actuated without any drag or resistancefrom the solenoids. At the same time, the circuits to the various signallights are arranged so that said circuits will still be closed upon thecorresponding contact strips and terminal strips becoming engaged.

,If no leveling action is desired, each of the blocks 30, before beingengaged with wire 61, is merely swung out of the way, turning ontrunnions 26 as an axis; the

flat side of member being then engaged with the spring-pressed roller28, yieldablypreventing any, undesired down-swing of the biock and partsattached thereto of themselves.

With the. described mechanism, the frame of the slab laying machine isaccurately maintained at a predetermined level and the slab thicknessclosely controlled, even though there may be some vertical deviation. intherailsrelative to such level,

From the foregoing description it: will. be readily seen that'therehasbeenproduced suchi at device as.wills,ub stantially fulfill theobjects of the invention, as set forth herein.

While this specification sets forth in detail the present and preferredconstruction of the device, still in practice such deviations from suchdetail may be resorted to as do not form a departure from the spirit ofthe invention, as defined by the appended claims.

Having thus described the invention, the following is claimed as new anduseful, and upon which Letters Patent are desired:

1. In a concrete slab laying machine which includes a frame structure,ground supported trucks on opposite sides of the frame structure, andvertical jack units connecting the frame structure and the trucks andproviding for vertical adjustment of the frame structure relative to thetrucks; ground supported grade wires extending along the path ofmovement of the machine to the sides of the same, and mechanisms on themachine to actuate the jack units independently of each other upondeviation of the frame structure from a predetermined level, saidmechanisms each including Wire engaging feeler elements.

2. A structure, as in claim 1, in which each mechanism includes normallyopen circuits, the closing of either of which actuates the correspondingjack unit in one direction or the other, and the feeler elementscomprise a pair of horizontal contact strips arranged to straddle thecorresponding wire in normally spaced relation thereto, and verticalterminal posts fixed with relation to the strips for engagement therebyand normally spaced therefrom, the posts and strips being interposed inthe circuits.

3. In a concrete slab laying machine which includes a frame structure,front and rear ground supported trucks on opposite sides of the framestructure, and vertical jack units connecting the frame structure andthe trucks and providing for vertical adjustment of the frame structurerelative to the trucks; a ground supported grade wire extending alongthe path of movement of the machine on each side of the same, andmechanisms on the machine to actuate the jack units independently ofeach other upon deviation of either side and end of the frame structurefrom a predetermined level, said mechanisms each including wire engagingfeeler elements mounted adjacent the corresponding jack unit.

4. In a concrete slab laying machine which includes a frame structure,ground supported trucks on opposite sides of the frame structure, andvertical jack units connecting the frame structure and the trucks andproviding for vertical adjustment of the frame structure relative to thetrucks; ground supported grade wires extending along the path ofmovement of the machine to the sides of the same, means to control themovement of each jack unit including a valve, normally idle electricdevices to actuate the valve, circuits for said devices, and normallyopen switches interposed in the circuits, said switches comprisingfeeler and contact strips arranged to straddle one of the grade wires innormally spaced relation thereto and transversely thereof.

5. In a concrete slab laying machine which includes a frame structure,ground supported trucks on opposite sides of the frame structure, andvertical jack units connecting the frame structure and the trucks andproviding for vertical adjustment of the frame structure relative to thetrucks; means to control the movement of each jack unit including apiston valve, normally idle electric devices to. actuate the valve,circuit for said devices, normally open switchesinterposed in saidcircuits, and a ground supported"element arranged'to cooperate with theswitches to alternately actuate the same upon undulating movement of themachine as it advances; said electrical devices comprising opposedaxially alined' and' separated solenoids, a common axially movable coreextending therehetween a lever. connected tothe core and valve piston,and means pivoting; tlielever intermediate its ends in a fixedposition.

6. A structure, as inclaim 5", in which the axes of'the core and valvepistonare" disposed" in parallelbut spacedapart relation.

7. A structure, as in claim 5, in which the lever extends beyond one ofthe pivot means to form a manually operable handle for actuating thevalve when the electrical devices are inactive.

8. In a concrete slab laying machine which includes a frame structure,ground supported trucks on opposite sides of the frame structure, andvertical jack units connecting the frame structure and the trucks andproviding for vertical adjustment of the frame structure relative to thetrucks; ground supported grade wires extending along the path ofmovement of the machine to the sides of the same, normally idlemechanism on the machine to actuate each jack unit and includingnormally inactive electrical devices, circuits for said devices,normally open switches in the circuits including vertically spacedflexible feeler and contact strips straddling the grade wiretransversely thereof and in normally spaced relation thereto andvertical terminal posts above and below the strips and normally spacedtherefrom, a block in which the strips and posts are mounted and formedwith a horizontal slot extending lengthwise of the strips and open atits outer end and in which the strips are exposed, and means mountingthe block on the machine adjacent the corresponding jack unit.

9. A structure, as in claim 8, in which the mounting means for the blockprovides for vertical adjustment thereof.

10. A structure, as in claim 8, in which the mounting means for theblock is arranged to provide for vertical swinging of the block to aposition clear of the wire while normally maintaining said block at adefinite level.

11. A structure, as in claim 8, in which the mounting means for theblock is arranged to provide for horizontal swinging of the block from anormal transversely projecting position, while yieldably maintaining theblock in said position.

12. A structure, as in claim 8, in which the mounting means for theblock is arranged to provide for horizontal swinging of the block from anormal transversely projecting position, while yieldably maintaining theblock in said position; and independently providing for verticalswinging of the block to a position clear of the wire while normallymaintaining said block at a definite level.

13. A structure, as in claim 8, in which the mounting means for theblock comprises a support secured on the jack unit and projectinglaterally out therefrom, a vertical shaft mounted in the support, an armunit projecting from and relatively turnable on the shaft and on theouter end of which the block is mounted, and means between the arm unitand support yieldably preventing rotation of the arm unit.

14. A structure, as in claim 13, in which the shaft is threaded, and thearm unit includes a hub screwed on the shaft and movable up and down thesame upon rotation of the shaft in opposite directions.

15. A structure, as in claim 8, in which the mounting means for theblock comprises a support secured on the jack unit and projectinglaterally out therefrom, an arm unit projecting laterally out from thesupport and on the outer end of which the block is mounted, said armunit comprising inner and outer portions, means mounting the innerportion on the support, horizontal pivot 7- 8 means connecting the armportions, and means yieldably is opened, but energization of theelectric devices by preventing swinging of the outer arm portion aboutsaid such closing of the normally open switches w1ll be prepivot means.vented.

16. A structure, as in claim 4, with means to operate I each valvemanually, signal lights, circuit means for 5 7 References Clted 1n thefile of thls Patent said lights included in part with said circuits, sothat UNITED STATES PATENTS the lights will be lit when the electricdevices are energized, and a normally closed switch for said circuitsar- 2295519 Mlmkm Sept 1942 2,489,196 Re1s1ng Nov. 22, 1949 ranged inconnection with said circuit means so that 2491275 D 13 1949 'd lightsmay be energized upon closing of said nor- 10 I 1 n Sal 2,747,292Durnler May 29, 1956 mally open switches and when the normally closedswitch

